feat(obj): add lv_obj_remove_event_cb

based on #2128

src/core/lv_obj.c

@@ -391,7 +391,37 @@ void lv_obj_add_event_cb(lv_obj_t * obj, lv_event_cb_t event_cb, void * user_dat
 
     obj->spec_attr->event_dsc[obj->spec_attr->event_dsc_cnt - 1].cb = event_cb;
     obj->spec_attr->event_dsc[obj->spec_attr->event_dsc_cnt - 1].user_data = user_data;
+}
 
+bool lv_obj_remove_event_cb(lv_obj_t * obj, lv_event_cb_t event_cb, void * user_data)
+{
+    LV_ASSERT_OBJ(obj, MY_CLASS);
+    if(obj->spec_attr == NULL) return false;
+
+    int32_t i = 0;
+    for(i = 0; i < obj->spec_attr->event_dsc_cnt; i++) {
+        if(obj->spec_attr->event_dsc[i].cb == event_cb) {
+            /*Check if user_data matches or if the requested user_data is NULL*/
+            if(user_data == NULL || obj->spec_attr->event_dsc[i].user_data == user_data) {
+                /*Found*/
+                break;
+            }
+        }
+    }
+    if(i >= obj->spec_attr->event_dsc_cnt) {
+        /*No event handler found*/
+        return false;
+    }
+
+    /*Shift the remaining event handlers forward*/
+    for(; i < (obj->spec_attr->event_dsc_cnt-1); i++) {
+        obj->spec_attr->event_dsc[i].cb = obj->spec_attr->event_dsc[i+1].cb;
+        obj->spec_attr->event_dsc[i].user_data = obj->spec_attr->event_dsc[i+1].user_data;
+    }
+    obj->spec_attr->event_dsc_cnt--;
+    obj->spec_attr->event_dsc = lv_mem_realloc(obj->spec_attr->event_dsc, obj->spec_attr->event_dsc_cnt * sizeof(lv_event_dsc_t));
+    LV_ASSERT_MALLOC(obj->spec_attr->event_dsc);
+    return true;
 }
 
 void lv_obj_set_base_dir(lv_obj_t * obj, lv_bidi_dir_t dir)

src/core/lv_obj.h

@@ -405,15 +405,26 @@ void lv_obj_add_state(lv_obj_t * obj, lv_state_t state);
 void lv_obj_clear_state(lv_obj_t * obj, lv_state_t state);
 
 /**
- * Add a an event handler function for an object.
+ * Add an event handler function for an object.
  * Used by the user to react on event which happens with the object.
- * An object can have multiple event handler. They will be called in the same the order as they were  added.
+ * An object can have multiple event handler. They will be called in the same order as they were added.
  * @param obj       pointer to an object
  * @param event_cb  the new event function
  * @param user_data custom data data will be available in `event_cb`
  */
 void lv_obj_add_event_cb(lv_obj_t * obj, lv_event_cb_t event_cb, void * user_data);
 
+/**
+ * Remove an event handler function for an object.
+ * Used by the user to react on event which happens with the object.
+ * An object can have multiple event handler. They will be called in the same order as they were added.
+ * @param obj       pointer to an object
+ * @param event_cb  the event function to remove
+ * @param user_data if NULL, remove the first event handler with the same cb, otherwise remove the first event handler with the same cb and user_data
+ * @return true if any event handlers were removed
+ */
+bool lv_obj_remove_event_cb(lv_obj_t * obj, lv_event_cb_t event_cb, void * user_data);
+
 /**
  * Set the base direction of the object
  * @param obj   pointer to an object